Still having "crushes" at 45.

[Fedupandemotional]

I know this is going to make me sound pathetic and needy yet I don't think I am generally.
I have a long history of depression on and off for the past 15 years. Even on medication I still have good and bad days. I am a single parent to a child with autism.
I have a poor history with relationships in that they never really happened for me. Partly I avoided them and partly because men don't seem to see me as relationship material if that makes sense.
Instead I have a history of crushes on unavailable men who are either married or otherwise not available. I'd never want to be the other woman so wouldn't act on my crush. On the other band it's getting frustrating in emotional heartache and energy. I feel sick, tearful and upset about my current crush who is very unavailable. It is getting me down.
Why do I do this to myself?
On another note I think I might well be asexual as I have no sexual feelings and tbh they have never been there. I got DS by forcing myself to have sex with my then husband who thought he could cope with my lack of desire ( in the end he couldn't). My GP says there is nothing she can do about my lack of sexual desire and that I just have a low libido.
So - my crushes are not sexual but emotional.
I am 45 now and feeling a total failure in life due to this.
45 and still having crushes. It's not good is it?

I though i was reading about myself there for a moment fedup, i am also a single mother with an autistic child and around a similar age, i have suffered with depression for many years i have also felt that i am asexual to the point i have googled it, i cant seem to be bothered with relationships and the ones that i have had ive ended them.
I used to get crushes on people that i know i could never have, i think it was because fantasy was better than reality but now i dont even have crushes anymore and would rather do a jigsaw, ive never really been interested in sex and usually had to be drunk or did it through a sense of duty.
I got married because thats what all my freinds were doing ( i know it sounds stupid ) and had 2 children, my DD is at uni and my DS lives at home with me.
I do have male freinds who have wanted to be more than freinds but im just not interested.
I have been on ADs for a few years and did wonder if that was the reason why i had a very low labido because that can be a side effect of ADs but when i think back to when i wasnt on them i wasnt interested in sex then either.
I put the way i feel mostly down to my parents who were emotionally cold ( no hugs or ever being told they loved me ) my father was an alcoholic, and my sadistic older brother who used to batter me at every oppertunity and make me feel worthless, also a couple of incidents when i was abused and not believed at the time,
now its as though i get in there first and ruin anything good before the other person can do it because in my mind im positive they will because im worthless and stupid and they are bound to find someone better so why bother.

Oh thank you bittersweet - it's a relief to know I am not alone. My latest crush is a priest who I suspect is gay (very camp anyway) so even if he WAS available he wouldn't be if you see what I mean. He's a nice guy anyway and we have a laugh together at times. I do wonder if it's the fact that he IS unavailable that's attractive because I cannot cope with the reality. I don't know........